include/linux/ring_buffer.h

   1 #ifndef _LINUX_RING_BUFFER_H
   2 #define _LINUX_RING_BUFFER_H
   3
   4 #include <linux/mm.h>
   5 #include <linux/seq_file.h>
   6
   7 struct ring_buffer;
   8 struct ring_buffer_iter;
   9
  10 /*
  11  * Don't refer to this struct directly, use functions below.
  12  */
  13 struct ring_buffer_event {
  14         u32             type_len:5, time_delta:27;
  15         u32             array[];
  16 };
  17
  18 /**
  19  * enum ring_buffer_type - internal ring buffer types
  20  *
  21  * @RINGBUF_TYPE_PADDING:       Left over page padding or discarded event
  22  *                               If time_delta is 0:
  23  *                                array is ignored
  24  *                                size is variable depending on how much
  25  *                                padding is needed
  26  *                               If time_delta is non zero:
  27  *                                array[0] holds the actual length
  28  *                                size = 4 + length (bytes)
  29  *
  30  * @RINGBUF_TYPE_TIME_EXTEND:   Extend the time delta
  31  *                               array[0] = time delta (28 .. 59)
  32  *                               size = 8 bytes
  33  *
  34  * @RINGBUF_TYPE_TIME_STAMP:    Sync time stamp with external clock
  35  *                               array[0]    = tv_nsec
  36  *                               array[1..2] = tv_sec
  37  *                               size = 16 bytes
  38  *
  39  * <= @RINGBUF_TYPE_DATA_TYPE_LEN_MAX:
  40  *                              Data record
  41  *                               If type_len is zero:
  42  *                                array[0] holds the actual length
  43  *                                array[1..(length+3)/4] holds data
  44  *                                size = 4 + length (bytes)
  45  *                               else
  46  *                                length = type_len << 2
  47  *                                array[0..(length+3)/4-1] holds data
  48  *                                size = 4 + length (bytes)
  49  */
  50 enum ring_buffer_type {
  51         RINGBUF_TYPE_DATA_TYPE_LEN_MAX = 28,
  52         RINGBUF_TYPE_PADDING,
  53         RINGBUF_TYPE_TIME_EXTEND,
  54         /* FIXME: RINGBUF_TYPE_TIME_STAMP not implemented */
  55         RINGBUF_TYPE_TIME_STAMP,
  56 };
  57
  58 unsigned ring_buffer_event_length(struct ring_buffer_event *event);
  59 void *ring_buffer_event_data(struct ring_buffer_event *event);
  60
  61 /**
  62  * ring_buffer_event_time_delta - return the delta timestamp of the event
  63  * @event: the event to get the delta timestamp of
  64  *
  65  * The delta timestamp is the 27 bit timestamp since the last event.
  66  */
  67 static inline unsigned
  68 ring_buffer_event_time_delta(struct ring_buffer_event *event)
  69 {
  70         return event->time_delta;
  71 }
  72
  73 /*
  74  * ring_buffer_event_discard can discard any event in the ring buffer.
  75  *   it is up to the caller to protect against a reader from
  76  *   consuming it or a writer from wrapping and replacing it.
  77  *
  78  * No external protection is needed if this is called before
  79  * the event is commited. But in that case it would be better to
  80  * use ring_buffer_discard_commit.
  81  *
  82  * Note, if an event that has not been committed is discarded
  83  * with ring_buffer_event_discard, it must still be committed.
  84  */
  85 void ring_buffer_event_discard(struct ring_buffer_event *event);
  86
  87 /*
  88  * ring_buffer_discard_commit will remove an event that has not
  89  *   ben committed yet. If this is used, then ring_buffer_unlock_commit
  90  *   must not be called on the discarded event. This function
  91  *   will try to remove the event from the ring buffer completely
  92  *   if another event has not been written after it.
  93  *
  94  * Example use:
  95  *
  96  *  if (some_condition)
  97  *    ring_buffer_discard_commit(buffer, event);
  98  *  else
  99  *    ring_buffer_unlock_commit(buffer, event);
 100  */
 101 void ring_buffer_discard_commit(struct ring_buffer *buffer,
 102                                 struct ring_buffer_event *event);
 103
 104 /*
 105  * size is in bytes for each per CPU buffer.
 106  */
 107 struct ring_buffer *
 108 __ring_buffer_alloc(unsigned long size, unsigned flags, struct lock_class_key *key);
 109
 110 /*
 111  * Because the ring buffer is generic, if other users of the ring buffer get
 112  * traced by ftrace, it can produce lockdep warnings. We need to keep each
 113  * ring buffer's lock class separate.
 114  */
 115 #define ring_buffer_alloc(size, flags)                  \
 116 ({                                                      \
 117         static struct lock_class_key __key;             \
 118         __ring_buffer_alloc((size), (flags), &__key);   \
 119 })
 120
 121 void ring_buffer_free(struct ring_buffer *buffer);
 122
 123 int ring_buffer_resize(struct ring_buffer *buffer, unsigned long size);
 124
 125 struct ring_buffer_event *ring_buffer_lock_reserve(struct ring_buffer *buffer,
 126                                                    unsigned long length);
 127 int ring_buffer_unlock_commit(struct ring_buffer *buffer,
 128                               struct ring_buffer_event *event);
 129 int ring_buffer_write(struct ring_buffer *buffer,
 130                       unsigned long length, void *data);
 131
 132 struct ring_buffer_event *
 133 ring_buffer_peek(struct ring_buffer *buffer, int cpu, u64 *ts);
 134 struct ring_buffer_event *
 135 ring_buffer_consume(struct ring_buffer *buffer, int cpu, u64 *ts);
 136
 137 struct ring_buffer_iter *
 138 ring_buffer_read_start(struct ring_buffer *buffer, int cpu);
 139 void ring_buffer_read_finish(struct ring_buffer_iter *iter);
 140
 141 struct ring_buffer_event *
 142 ring_buffer_iter_peek(struct ring_buffer_iter *iter, u64 *ts);
 143 struct ring_buffer_event *
 144 ring_buffer_read(struct ring_buffer_iter *iter, u64 *ts);
 145 void ring_buffer_iter_reset(struct ring_buffer_iter *iter);
 146 int ring_buffer_iter_empty(struct ring_buffer_iter *iter);
 147
 148 unsigned long ring_buffer_size(struct ring_buffer *buffer);
 149
 150 void ring_buffer_reset_cpu(struct ring_buffer *buffer, int cpu);
 151 void ring_buffer_reset(struct ring_buffer *buffer);
 152
 153 int ring_buffer_swap_cpu(struct ring_buffer *buffer_a,
 154                          struct ring_buffer *buffer_b, int cpu);
 155
 156 int ring_buffer_empty(struct ring_buffer *buffer);
 157 int ring_buffer_empty_cpu(struct ring_buffer *buffer, int cpu);
 158
 159 void ring_buffer_record_disable(struct ring_buffer *buffer);
 160 void ring_buffer_record_enable(struct ring_buffer *buffer);
 161 void ring_buffer_record_disable_cpu(struct ring_buffer *buffer, int cpu);
 162 void ring_buffer_record_enable_cpu(struct ring_buffer *buffer, int cpu);
 163
 164 unsigned long ring_buffer_entries(struct ring_buffer *buffer);
 165 unsigned long ring_buffer_overruns(struct ring_buffer *buffer);
 166 unsigned long ring_buffer_entries_cpu(struct ring_buffer *buffer, int cpu);
 167 unsigned long ring_buffer_overrun_cpu(struct ring_buffer *buffer, int cpu);
 168 unsigned long ring_buffer_commit_overrun_cpu(struct ring_buffer *buffer, int cpu);
 169 unsigned long ring_buffer_nmi_dropped_cpu(struct ring_buffer *buffer, int cpu);
 170
 171 u64 ring_buffer_time_stamp(struct ring_buffer *buffer, int cpu);
 172 void ring_buffer_normalize_time_stamp(struct ring_buffer *buffer,
 173                                       int cpu, u64 *ts);
 174 void ring_buffer_set_clock(struct ring_buffer *buffer,
 175                            u64 (*clock)(void));
 176
 177 size_t ring_buffer_page_len(void *page);
 178
 179
 180 void *ring_buffer_alloc_read_page(struct ring_buffer *buffer);
 181 void ring_buffer_free_read_page(struct ring_buffer *buffer, void *data);
 182 int ring_buffer_read_page(struct ring_buffer *buffer, void **data_page,
 183                           size_t len, int cpu, int full);
 184
 185 struct trace_seq;
 186
 187 int ring_buffer_print_entry_header(struct trace_seq *s);
 188 int ring_buffer_print_page_header(struct trace_seq *s);
 189
 190 enum ring_buffer_flags {
 191         RB_FL_OVERWRITE         = 1 << 0,
 192 };
 193
 194 #endif /* _LINUX_RING_BUFFER_H */